JPH10208941A - Chip inductor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip inductor the coil of which has a large degree of freedom in number of turns and which can be manufactured inexpensively in an even manufacturing time by arranging conductive patterns corresponding to coil sections and terminal electrodes on both surfaces of an insulating substrate in grid-like states and providing through holes having internal surfaces coated with conductors. SOLUTION: A core having a square cross section is made of an insulating material, such as glass, composite material, ceramic, etc., and a conductive pattern 2 on the upper surface of the core 1 constitutes part of a coil. The lower surface of the core 1 also has a conductive pattern. A coil 5 wound around the core 1 is formed of the conductive patterns 2 on the upper and lower surfaces of the core 1 and the conductive sections 3 on both side faces of the core 1 by connecting the conductive patterns 2 to each other through the conductive sections 3. In addition, terminal electrodes 4 are provided at both ends of the core 1. Furthermore, the conductive sections 3 constitute parts of the conductors covering the internal surfaces of through holes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip inductor suitable for electronic devices manufactured by surface mounting technology.

[0002]

2. Description of the Related Art In recent years, a circuit structure of a surface mounting method has been spreading along with miniaturization of electronic equipment, and an inductance component, that is, a chip inductor as shown in FIG. 5 has been known. FIG. 5A shows a spiral coil 52 formed on the surface of an insulating substrate 51 using a conductive material such as copper.
It is seen in the issue. 5B, the surface of the core 53 of the columnar insulator is coated with a conductive material such as copper by plating, and a part of the conductive film is spirally removed as shown by 54 with a laser beam or the like. Thus, the coil 55 is formed.

[0003]

Although the above-mentioned conventional chip inductors are each useful, they have the following problems. That is, in the case of FIG. 5A, since the coil, which should be three-dimensional, is formed into a spiral plane pattern, the number of turns of the coil cannot be increased, and a coil having a very large inductance cannot be obtained.
On the other hand, the one shown in FIG. 5B requires expensive equipment such as a laser processing machine for the production, and if the number of coil turns is increased, the amount of the conductive film to be removed increases. Processing time increases and production costs increase. SUMMARY OF THE INVENTION The present invention solves these problems, and provides a chip inductor having a large degree of freedom in the number of turns of a coil, which can be manufactured at low cost in a uniform manufacturing time regardless of the number of turns, and a method of manufacturing the same.

[0004]

A chip inductor according to the present invention has a coil formed of a conductive pattern wound around a winding core having a substantially rectangular cross section, similar to that shown in FIG. 5B. Structure. As a method of manufacturing the same, a conductive pattern corresponding to a coil portion and a terminal electrode of a chip inductor is provided on both sides of a single insulating substrate, which is a material of a winding core, in a length and width corresponding to a plurality of chip inductors. A through-hole group whose inner surface is covered with a conductor is provided, and the conductive patterns on both surfaces of the substrate are electrically connected to connect the through-hole group or a direction crossing the through-hole group. By cutting the substrate into multiple pieces, a large number of chip inductors are obtained from one substrate material.

Accordingly, the conductive patterns formed on both sides of the substrate become portions of the coil winding of the chip inductor on the upper and lower surfaces of the winding core and terminal electrodes, and the conductive portion on the inner surface of the through hole is formed of the winding of the coil winding. It is the part on both sides of the core and the part connecting the terminal electrodes on the upper and lower surfaces. As for the through hole, a method of providing a small circle for each turn of the coil and providing an elongated through hole extending over a plurality of coils to remove unnecessary portions from the conductive portion on the inner surface of the through hole. Therefore, there is a method of forming a plurality of coils with one long hole through hole. That is, the present invention is to manufacture a chip inductor having excellent performance by the same equipment and method as used for manufacturing a normal printed circuit board.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is an external view of a first embodiment of a chip inductor according to the present invention. Reference numeral 1 denotes a winding core having a square cross section, which is made of an insulating material such as paper, glass, a composite material, or ceramics, and may be any other material for a printed circuit board. Reference numeral 2 denotes a conductive pattern on the upper surface of the winding core, which forms a part of the coil. Although not visible in the drawing, the lower surface also has the conductive pattern. Reference numeral 3 denotes conductive portions provided on both side surfaces of the winding core, which connect the conductive patterns on the upper and lower surfaces, thereby forming a coil in which the conductive patterns on the upper and lower surfaces of the winding core and the conductive portions on both side surfaces are wound on the winding core. Has formed. 4 at both ends are terminal electrodes.
In FIG. 1A, the reason why the conductive portion 3 on the side surface is an arc-shaped groove is that this portion is the remaining portion of the through hole provided in the substrate in the manufacturing process. That is, the conductive portion 3 is a part of the conductor covering the inner surface of the through hole. FIG.
(B) schematically shows the state of the coil 5 thus formed.

Next, a description will be given of a method of manufacturing such a chip inductor in a large number from one substrate. FIG.
As shown in the figure, a substrate 2 made of an insulating material serving as a winding core
Prepare 1 FIG. 2A shows the upper surface of the substrate, and FIG. 2B shows the lower surface of the substrate. Each area separated by the vertical and horizontal boundaries 22 and 23 becomes an individual chip inductor when completed. Conductive patterns 24 and 25 are formed on both surfaces of the substrate, respectively.
The formation of the conductive patterns 24 and 25 can be performed by manufacturing a printed circuit board, such as a method of removing unnecessary portions by covering the entire surface of the board with copper foil, or a method of forming a pattern on a board material with a conductive material. It depends on the method usually used.

A large number of through holes 26 and 27 are provided on a substrate 21 along boundaries 22 and 23, and a conductive portion for electrically connecting conductive patterns on both surfaces of the substrate is formed on the inner surface of the through hole. The formation of the through-hole also depends on the method of manufacturing the printed circuit board, such as electroless plating of a conductor after drilling. Reference numeral 28 is a reference hole used for pattern alignment or the like when processing the substrate.

The conductive pattern 24 on the upper surface of the substrate shown in FIG.
Are parallel to the horizontal direction, but the conductive pattern 25 on the lower surface of the substrate in FIG.
Are arranged to connect through holes belonging to patterns adjacent to each other. After forming the conductive patterns and the through-hole groups on both surfaces of the substrate in this manner, the boundary lines 22 and 23 are formed.
The substrate is cut by dicing, slicing, or the like along the line, and separated into individual small portions. Each part thus obtained becomes a chip inductor as shown in FIG.

In FIG. 2, the through holes 26 connecting the terminal electrode patterns on both surfaces of the substrate are
Through holes 27 that become part of the coil
Are arranged along the vertical boundary line 23. In the substrate cutting step, the substrate is cut vertically and horizontally along the boundary lines 22 and 23. However, the through holes 26 for the terminal electrodes are also formed along the vertical boundary line 23. 23, and a long hole extending substantially over the entire width of the substrate is provided along the horizontal boundary line 22 instead of the through-hole group.
By simply separating the substrate along 3, the individual chip inductors can be separated.

Next, a second embodiment of the chip inductor of the present invention will be described. FIG. 3 shows its appearance. Figure 1 above
1, a coil composed of a conductive pattern 32 on the upper surface, a conductive pattern 33 on the side surface, and the like is wound around a winding core 31 of an insulator having a rectangular cross section, and a terminal electrode 34 is provided. The difference is that the conductive pattern 33 on the side surface of the winding core is not a groove but a flat surface, which is due to a difference in manufacturing method.

FIG. 4 shows a method of manufacturing the chip inductor of FIG.
This will be described below. In this case as well, a large number of individual substrates are manufactured. That is, each portion of the substrate 41 made of an insulating material serving as a winding core, divided by vertical and horizontal boundaries 42 and 43, becomes an individual chip inductor. FIG. 2 showing the first embodiment shown in FIG.
A conductive pattern 44 similar to (A) and (B) is formed. However, unlike the first embodiment, one through hole is not provided for each winding of the coil, but an elongated through hole 45 is formed that extends over a plurality of chip inductors in which the axis of the coil is straight. Instead of providing a conductive portion that covers the entire inner periphery of the elongated hole 45,
A portion serving as a coil winding on the side surface of the winding core and a conductive pattern 46 serving as a portion for connecting terminal electrode patterns on both surfaces of the substrate are dispersedly provided at a plurality of locations.

The formation of the individual conductive patterns 46 on the inner surface of the long hole 45 is performed in the same manner as in the manufacture of a printed circuit board, for example, by cutting out the long hole using an end mill and performing electroless plating. After the conductive portion is formed on the entire inner peripheral surface by photolithography, unnecessary portions are removed by photolithography. Incidentally, reference numeral 47 denotes a reference hole at the time of processing.
After forming the conductive pattern 44 on both surfaces of the substrate 41 and forming the conductive pattern 46 on the inner periphery of the long hole 45,
The substrate is cut along the boundaries 42 to separate into individual parts. Each of the obtained small pieces becomes a chip inductor as shown in FIG.

In the chip inductor of the first embodiment, the minimum pitch of the coil winding is limited by the restriction of the density of through holes that can be arranged in a fixed length, and therefore the number of turns is also limited by this. On the other hand, in the second embodiment, a step of removing unnecessary portions of the conductor on the inner surface of the through hole is required after the formation of the through hole. Can be made smaller, a chip inductor having the same number of turns as the first one can be manufactured more compactly, and the number of turns can be increased if the dimensions are the same.

Through the above first and second embodiments, in designing the manufacturing process, the order of the formation of the conductive patterns and the formation of the through holes on both surfaces of the substrate may be arbitrarily selected. Also,
If necessary, a step of plating the terminal electrode or insulatingly covering the coil portion can be provided.

As the substrate material for the winding core, a flexible material such as a polyimide film can be used in addition to the rigid plate material as described in the above embodiment. If a large-sized product is made using a flexible material, the finished coil will also have flexibility, and thus the obtained coil will not be limited to the range of chip inductors. Can open. For example, if such a coil is used for an antenna of a small communication device, it can be curved and disposed inside the device, which is impossible with a conventional rigid ferrite bar antenna or the like. It is extremely useful in constructing.

[0017]

Examples of the manufacturing process according to the present invention will be described below. Regarding the first embodiment, Photolithography is performed on a substrate having copper foil coated on both surfaces to form conductive patterns on both surfaces of the substrate. 2. A large number of holes are drilled or pressed. 3. Cover the inner surface of the hole with a conductor by electroless plating,
Form a through hole. 4. The substrate is cut along the boundaries to obtain individual chip inductors.

In the second embodiment, Step 1
Is common to the above, and the process after step 2 is as follows. 2. Multiple long holes are drilled in the substrate by end milling or pressing. 3. The substrate is subjected to electroless plating, and a conductor is coated on the inner surface of the elongated hole to form an elongated through hole. 4. A protective resist is applied to the entire inner peripheral surface of the long hole and the resist is exposed only to a portion required as an electrode by the transmitted light of the film on which the pattern is recorded, and the unexposed portion is removed by washing. 5. The portion of the conductor without the resist film is removed by etching. 6. The protective resist film is dissolved and removed. 7. The substrate is cut along the boundaries to obtain individual chip inductors. The above is merely an example, and various process designs are possible within the scope of the present invention to manufacture the chip inductor of the present invention.

[0019]

As described above, according to the present invention, it is possible to manufacture a small, high-performance chip inductor by using the manufacturing equipment and technology for a printed circuit board. An expensive processing machine or a special processing method is not required for manufacturing, and since a large number of pieces can be obtained from one substrate, productivity is extremely high. As a result, reductions in processing man-hours and mass production, which were not possible in the past, have been realized, and small and high-performance surface-mounted chip inductors can be provided at a low price, while contributing to the miniaturization and cost reduction of electronic devices. .

[Brief description of the drawings]

FIG. 1 is a first embodiment of a chip inductor according to the present invention, (A) is an external view thereof, and (B) is a schematic diagram of a coil structure.

FIGS. 2A and 2B are drawings of a substrate for manufacturing the chip inductor of FIG. 1 in multiple pieces, wherein FIG. 2A shows the upper surface of the substrate and FIG. 2B shows the lower surface of the substrate.

FIG. 3 is an external view of a second embodiment of the chip inductor according to the present invention.

FIG. 4 is a perspective view of a substrate for manufacturing the chip inductor of FIG. 3 in multiple pieces.

FIG. 5 is an external view of a conventional chip inductor.

[Explanation of symbols]

1, 31, 53 winding core 2, 24, 25, 32, 33, 44, 46 conductive pattern 3 conductive part 4, 34 terminal electrode 5 coil 21, 41 substrate 22, 23, 42, 43 boundary line 26, 27 through hole 45 through hole

Claims (3)

[Claims] 1. A chip inductor comprising a coil formed by forming a conductive portion on the upper and lower surfaces and both side surfaces of a winding core having a substantially rectangular cross section with an insulating material, and the conductive portion being spirally wound around the winding core. The conductive portions on the upper and lower surfaces of the core are part of the conductive pattern formed on both surfaces of the substrate which is the material of the core in the manufacturing process, and the conductive portions on both sides are the inner surfaces of the through holes provided on the substrate in the manufacturing process. A chip inductor, which is a part of a conductor that has coated a chip. 2. The method of manufacturing a chip inductor according to claim 1, wherein regions corresponding to the plurality of chip inductors are arranged in a grid pattern on an insulating substrate, and chips are provided on both surfaces of the substrate. Forming a conductive pattern corresponding to portions of the coil winding of the inductor on the upper and lower surfaces of the chip inductor; and forming a plurality of through-holes on the inner surface of a conductor that electrically connects the conductive patterns on both surfaces of the substrate. A process of linearly arranging a plurality of rows at positions corresponding to the portions on both sides of the coil winding of each chip inductor, and a process of cutting the substrate along a straight line connecting through holes. A method for manufacturing a chip inductor, comprising obtaining a plurality of chip inductors from one substrate. 3. The method of manufacturing a chip inductor according to claim 1, wherein regions corresponding to the plurality of chip inductors are arranged in a grid on an insulating substrate, and chips are provided on both surfaces of the substrate. A step of forming a conductive pattern corresponding to portions of the coil winding of the inductor on the upper and lower surfaces of the chip inductor; and a through hole formed on the inner surface of a conductor electrically connecting the conductive patterns on both surfaces of the substrate. Forming a plurality of rows of elongated through holes extending in the coil axis direction across the plurality of chip inductors, and a portion corresponding to a coil winding on both side surfaces of each chip inductor from the conductor on the inner surface of the elongated hole through hole; A step of removing other parts except for a part necessary for connection of the conductive pattern on both surfaces of the substrate, and cutting the substrate in a direction intersecting the length of the long through hole. A plurality of chip inductors from one substrate by a process including a step of: